O.K. I put new Wagner ceramic pads on my wife's STS. It has 60,000 miles and didn't really need then but I did it anyway. I had the rotors turned by a reputable shop even though they could have been used without that. The job was super easy and the brakes work great. Except they are dragging. When you stop and jack up the front wheel, either side, you cannot turn the tire/wheel. Take off the wheel/tire and you cannot turn the rotor even with a reasonable sized bar. Loosening the bleeder screw lets you know there is no hydraulic pressure present. You can then pry the pad in a little and the rotor will turn fine. Applying brakes again will relock them although they can be turned with considerable effort. I then removed the caliper bolts and pins and cleaned the pins and the tunnel they slide in. I used choke cleaner spray, gun cleaner spray, a gun barrel cleaning rag on a stick and then cleaned the slider pin. I lubed it with anti-seize and reinstalled the brakes. The rotor turned fine until I applied the brakes again. It locked again. Both sides were done and the result is the same. So there is no hydraulic pressure present and the sliders have been cleaned and lubed. The pads can be moved away from the rotors so that they will turn, therefore they are not simply so thick that the rotors are dragging. What in the world can be the problem? What have I overlooked? I have been doing vehicle maintenance for 48 years and this is ridiculous. Please send me the answer. Thanks.

1BadCadSTS

12-01-12, 10:19 PM

Sounds like bad calipers. Seized pistons.

oldmike

12-02-12, 10:48 AM

thanks, I had forgotten that this happens with phenolic pistons. I have had this happen before on a mcycle and a Dodge van. Are you aware of any method to check for this other than the dragging seems to be from nothing else. I mean without disassembling the calipers. The pistons seem to travel o.k. but were admittedly just a little harder than I expected to compress.

KRSTS

12-02-12, 11:47 AM

I would just replace the calipers, and while your at it put fresh brake fluid in.

1BadCadSTS

12-02-12, 12:46 PM

The fact they are not recending back in after being pressed out with hydraulic fluid is your proof.

scott9001

12-02-12, 02:44 PM

crack the bleeder open and make sure that there is a steady drip for a few seconds that will leave you with the fact that the flex hose hasent collapsed if you have a steady drip then you have a siezed caliper. is it the fact that the caliper is siezed tho or you did not cleane the mounting surfaces for the pads and they can not slide properly... did you clean the rust and put new hardware on when you were in there?

oldmike

12-02-12, 05:38 PM

I did not clean them any better than I cleaned hundreds of brake jobs in the past. But if for some reason this model of Cadillac is unusually touchy then there may be a problem there as the roads down here are crusted with salt from the ocean. Nor did I install any new hardware as I consider 60,000 miles very few for the OEM stuff. I do not drive very hard but I admit my wife only knows two things - press the gas pedal or press the brake pedal. A thorough test for the brake system at every stop sign or traffic light. She has wrecked 12 of our cars, some beyond recognition. Not counting minor scrapes. I have never heard of changing the brake fluid regularly especially as it looks like water right now. Is this needed? I have put a lot of miles on a lot of Cadillacs and so far this 2005 STS is the worst of the lot. Period.

oldmike

12-07-12, 10:12 AM

In case any of you are still interested. I bought new calipers and the new Wagner pads I had just installed would not fit the new calipers with shims in place. Looking very carefully at the pads I saw that the coating applied to forestall rust and quieten the brakes had created what appeared to be "casting flash" at the edges of the pad ends where they are supposed to glide in and out. The coating was harder and sharp compared to bare pad backing on the OEM pads and it was digging into the shims. Barely and leaving hardly any trace but as there is no real force pulling the pads back from the rotor it was enough to stop them cold. I filed the ends of the pads clean and wire brushed them and re-installed them. The brakes now work fine but the right front squeaks until 15mph is attained. I guess I would have to say buy pads but look closely at the ends that ride in the calipers. Thanks for all the replies. Scott 9001 came closest to the problem although it was not rust it was a similar problem going on.